Many tracking technologies can be used in the coal mine setting. One of them, reader-based tracking is similar to that which is utilized at retail outlets. It is comprised of two main components: a device known as readers to detect that tags are present as well as their tags.
In mining, there are two variants in the reader-based method. In one, referred to as zone-based RFID, the tag is inserted on every miner, and readers are placed at certain places in the mine. In the alternative that is known as reverse-RFID, the miner wears tiny readers, and tags are placed in known places in the mine. You can visit www.nltdigital.com/ for underground tracking.
Another method (node-based tracking) doesn't use tags. It relies on a complex analysis of signals in the RF spectrum that pass between radio and several nodes to determine the distance between those radios to the other nodes.
The final technology for tracking to be examined is Inertial Tracking using sensors worn by miners to track accelerations and changes in the magnetic field of the earth and the changes in the angular speed of the miner, to determine the shift in the location of the miner.
The location of the miner would be determined based on these changes using a tiny machine worn by the miner or the information about changes can be sent to a central system at the center of operations for mining. In any case, a connection to the communication system would be needed to relay the information about the location on the ground.
At the time of writing Inertial tracking systems are in development, which means that the review on this subject is a bit limited.